8000

• UCREFRP Catalog Number: 8000
• Author: Werth, L. F., et al.
• Title: Developing a Geographic Information System for Resources Monitoring on the Colorado River in the Grand Canyon.
• USFW Year: 1993.
• USFW - Doc Type: R-93-20,
• Copyright Material: NO

completed, all point, line, and polygon data are attributed. A quality check is performed on
the attributed master coverage by plotting the line work and attribute labels to a hard copy.
The hard copy plot is then quality checked by cross referencing it with the original
classification mylar.
At this time, the master coverage is segregated by attribute into separate coverages and
placed into the previously mentioned directory structure. Data sets currently being developed
by the Remote Sensing and Geographic Information Section for the GCES/GIS and the
directories they reside in can be seen in appendix D. A sample plot of the data set generated
for site No. 4 can be seen on figure 11 as a foldout at the back of this report.
A concern about the quality of the initial base surveying was identified during the fall of
1991. A NPS geodist notified GCES that the maps for site No. 5 may fall short of National
Map Accuracy Standards because of a horizontal and vertical error found in the control points
used to produce the maps.
To assess the level of quality, the maps for sites No. 1, 2, and 5 were checked to see if they
met National Map Accuracy Standards. The easting (x) and northing (y) accuracy of points
used to produce the base maps were checked by GPS and conventional surveying. A team
from the APO (Arizona Projects Office) resurveyed the control points on the rim and the
points down on the canyon bottom. APO ran an open traverse from GPS points at the
beginning and end of each monitoring site. They also completed a vertical profile from some
of the control points to river's edge. The accuracy of the control points was well within the
tolerance to compile topographic maps with a 1-meter contour accuracy. Upon completion of
the analysis, the maps were determined to be within National Map Accuracy Standards. A
random topographic check using cross sectional surveying techniques is being performed by
the GCES survey crew on monitoring sites No. 3 and 6 through 15.
DISCUSSION
Long-Term Monitoring
To achieve the goals defined by the NRC (National Research Council) (1987), the GCES
enlisted the expertise of Reclamation's Remote Sensing and Geographic Information Section
in the development of a GIS data base to be used in the long-term monitoring of the Grand
Canyon. "If a management plan is to be developed for the Glen Canyon Dam, the plan
should be integrated with and based upon a sound understanding of the effects of operations
on environmental resources. The predictions of effects should be viewed as working
hypotheses about river processes; these hypotheses can be tested by use of monitoring data."
(NRC, 1987)
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